"I don't know. Apparently it's in his contract," said head coach Mike Munchak. "I don't know how we gave him a contract that allows him to take personal days on a game day. More evidence it is the worst contract a football team has ever given a player."
Johnson said the reasons for his personal day "aren't anyone's business," but later admitted he "needs a mental health day."
"I'm just spent from running behind my shitty offensive line," said Johnson, who has just 210 yards on the season on 2.9 yards per carry. "So I'm just going to crash on the couch and watch movies and get some take-out. I'll get refreshed and play again next week."
Steelers head coach Mike Tomlin admitted the news of Johnson's personal day will impact Pittsburgh's game plan.
"Any late change like this affects you," he said. "We've had our scout team back tiptoeing and stutter stepping all week behind the line of scrimmage. Now we'll have to prepare for someone who runs forward. We'll cope the best we can."
Munchak hopes Johnson's personal day will turn Tennessee's season around.
"Our running game can't get worse," he said. "Maybe Darius Raynaud will give us the boost we need. If so, he could be our starting running back going forward. Chris reminded me he has four more personal days in addition to three weeks of vacation."